Planar magnetron sputtering method and apparatus

Abstract

A planar magnetron sputtering apparatus is provided with an additional, variable magnetic field normal to and substantially throughout the erosion region of a cathode plate. Application of the foregoing variable magnetic field effects continuous variations in the general location of the points at which magnetic lines of flux are parallel to the cathode plate which correspondingly results in variations in the points of maximum cathode plate erosion. By producing a less acute erosion pattern over a wider cathode plate area, a greater portion of the cathode plate material may be sputtered from any particular planar cathode plate.

What is claimed is: 
     
       1. A method of increasing the amount of material which can be sputtered from the target plate of a planar magnetron cathode wherein a glow discharge plasma is magnetically confined to an annular region adjacent to the target plate, comprising: magnetically shifting a portion of the glow discharge plasma in a direction parallel to the target plate.   
     
     
       2. A method of increasing the extent of the erosion region of a sputtering source in a sputtering apparatus wherein a glow discharge plasma is magnetically confined to a closed loop region adjacent to the source by lines of magnetic flux which emerge from the source and return thereto along a curved path, comprising: magnetically shifting a portion of the glow discharge plasma across the target plate.   
     
     
       3. Apparatus for sputtering increased amounts of material from a planar sputtering source comprising anode means spaced from said source for establishing an electrostatic field therebetween, first magnet means for providing flux lines exiting said source and returning thereto along a curved path thereby defining an erosion region on said source in a closed loop configuration, second magnet means adapted to produce an auxiliary, variable magnetic field in a direction substantially normal to said source in the presence of said flux lines such that upon variation of said variable magnetic field, the location at which resultant flux lines are generally parallel to said source is continuously translated across said erosion region whereby said source is eroded to a generally uniform depth substantially throughout said erosion region. 
     
     
       4. Apparatus as defined in claim 3 wherein said second magnet means comprise an electromagnetic coil disposed in a surrounding relationship with respect to said source and substantially co-planar therewith. 
     
     
       5. Apparatus as defined in claim 4 wherein said second magnet means includes means for supplying an a.c. potential to said coil such that said variable magnetic field is generated. 
     
     
       6. Apparatus as defined in claim 3 wherein said first magnet means comprise a plurality of permanent magnets spaced in a closed loop array. 
     
     
       7. Apparatus as defined in claim 6 additionally comprising means for cooling said source upon energization of said source, anode means and said second magnet means. 
     
     
       8. An improved cathode sputtering device of the type including a flat target plate on which an annular erosion region is formed, and a first magnetic means for confining a glow discharge plasma to an annular region adjacent to the target plate by producing lines of magnetic flux which emerge from the target plate, arc into the glow discharge region in which there are points at which the magnetic field is parallel to the target plate, and re-enter the target plate, the improvement comprising: a second magnetic means for producing a variable magnetic field which enables the points in the glow discharge region at which the lines of flux are parallel to the target plate to be translated across the target plate whereby the extent of the annular erosion region is increased.   
     
     
       9. The cathode sputtering device of claim 8 wherein the second magnetic means comprises a coil which encircles the target plate and which can be energized to produce an electromagnet. 
     
     
       10. In a cathode sputtering device of the type including a sputtering source on which a closed loop erosion region is formed, and first magnetic means for confining a glow discharge plasma to a closed loop region adjacent to the sputtering source by producing lines of magnetic flux which emerge from the sputtering source and return thereto along a curved path, the improvement comprising: second magnetic means for producing a variable magnetic field which enables the curved path portions of the lines of magnetic flux to be translated across the sputtering source whereby the extent of the closed loop erosion region is increased.